The present invention relates to a fuel cell that is composed of stacked cells.
Power generation cells of a polymer electrolyte fuel cell each include a membrane electrode assembly (so-called MEA) and a pair of separators sandwiching the membrane electrode assembly. The membrane electrode assembly has an electrolyte membrane made of an ion-exchange membrane and a pair of electrodes sandwiching the electrolyte membrane. Then, fuel gas (for example, hydrogen gas) is supplied to a gas passage formed between one of the pair of separators and the membrane electrode assembly, and oxidation gas (for example, air) is supplied to a gas passage formed between the other separator and the membrane electrode assembly.
Typically, a fuel cell is configured by stacking a plurality of power generation cells together. The fuel cell has in it an introducing conduit, which distributes and introduces a power generation gas to the gas passages of the power generation cells, and a discharging conduit, which merges flows of the power generation gas after passing through the gas passages and discharges the merged flow.
Japanese Laid-Open Patent Publication No. 2009-164051 discloses such a fuel cell that has end cells provided at the ends in the stacking direction of a plurality of power generation cells. The end cell is composed of, for example, a plate and a pair of separators sandwiching the plate. A bypass passage is formed between the plate and each separator. The bypass passage connects the introducing conduit and the discharging conduit to allow the power generation gas to flow therethrough.
The end cells are configured not to generate power and exert a heat insulating effect at the ends in the stacking direction of the power generation cells. Such end cells limit temperature drop of the power generation cells arranged at the ends in the stacking direction, thereby suppressing generation of water due to condensation or the like inside the power generation cells.
Generation of water due to condensation or the like can occur not only inside the power generation cells, but also in the gas supply passage, which supplies the power generation gas to the inside from the outside of the fuel cell. Such water in the gas supply passage can be carried away by gas flow in order to enter the power generation cells in order to stay. This reduces the amount of gas supplied to the membrane electrode assembly and thus may decrease the power generation efficiency.